The bug has been fixed for in version 188.8.131.52
Important for Child Theme users
The @import can be removed from the style.css in the child theme. This is all done in the parent theme. The reason is that this will allow to load the sites faster. See the link for more info.
The example child theme has also been updated.
Please see the rest of the changes in the changelog.
[!] Fix responsive design bug
Here is the changelog on GitHub
Here is the diff from the trac